Generally, shuttle transfer units, of the general type of which the present invention is concerned, typically include a fixed frame spanning across a plurality of work stations. The shuttle transfer unit transports a workpiece between work stations, and each work station typically performs some type of manufacturing or assembly process on the workpiece.
When these shuttle transfer units load and unload the workpiece to and from the work stations, the workpiece must be orientated in a proper manner to allow for the proper fixturing and processing of the workpiece in the associated work station. This can become a rather difficult task when the workpieces have rather large and irregular geometries, such as motor vehicle chassis and frames.
Often, such motor vehicle frames and chassis must be rotated or rolled over 180.degree. such that both sides of the chassis or frames may be made accessible for various types of machining and welding processes. Currently, due to the size and shapes of such workpieces, the workpieces are typically re-orientated or rotated at a separate work station. The workpieces are then transported to a subsequent work station wherein the workpieces are fixtured for subsequent sequential processing of the workpiece. Such handling of the workpiece requires the additional space, equipment and time required for simply re-orientating the workpiece with respect to the production line. In addition, each work station requires the workpiece to be clamped or fixtured, thus requiring new datums and references to be established and thereby increasing the range of tolerances. Obviously, such processing breeds inefficiencies and is undesirable in a production environment.
It would be desirable to provide a shuttle transfer unit that re-orientates a large, irregular workpiece, such as a motor vehicle chassis or frame, while transferring the workpiece from one work station to a subsequent work station without requiring the need for a separate and additional work station for re-orientating the workpiece.